With the increasing importance of the Internet or xe2x80x9cWorld Wide Webxe2x80x9d, the Internet protocol is increasingly influencing the design of existing and future communications networks. The currently used and standardized Internet protocolxe2x80x94in particular Internet Protocol Version 4xe2x80x94is packet-oriented, that is to say the information to be transmitted is packed into data packets. These Internet data packets are in each case preceded by an Internet data packet header, in which a source and destination address, comprising 32 bytes, is stated. 128 bytes are provided for both the source address and the destination address in a future planned version. With the aid of a current or a future Internet protocol, a communication link is produced between Internet communications terminals, that is to say in particular computers, with the communications terminals being connected directly via xe2x80x9cpoint-to-pointxe2x80x9d data links.
Owing to the considerable rate of growth of the Internet, additional infrastructures need to be provided for this purpose, and the communications networks need to be adapted or added to. One possible adaptation is represented by Internet switching devicesxe2x80x94called routers or gateways in the specialist world and referred to as routers in the following textxe2x80x94which are used in the edge region of communications networks as access routers or gateways (edge routers) and, in the communications network itself, as special Internet routers. Communications network concepts for the transmission of Internet data packets in which the routers are produced using ATM technology (Asynchronous Transfer Mode) have been under discussion for a long time. In this case, in the access routers or else in the access network associated with the access router, the Internet data packets are packed in ATM cells and transmitted, via the ATM communication network, to special Internet ATM routers. These Internet ATM routers are connected to specific ATM communications systems in the ATM communications network like a server, and provide a virtual Internet overlay network which is superimposed on the ATM communications network, with the Internet ATM routers essentially being connected via permanent virtual connections (PVC) and semi-permanent virtual connections (SPVC).
This concept with additional xe2x80x9cedgexe2x80x9d routers and special ATM routers in ATM communications networks means that, with increasing acceptance and widening use of the Internet, there will be, owing to the additional routing functions in the ATM communications systems to and from the Internet ATM routers, a considerable additional traffic load on the ATM communications systems in the ATM communications networks, leading to a reduction in the transmission service for the data and data packets for other services.
EP 0 597 487 A2 discloses a communications system in which data packed into ATM cells and data packets packed into ATM cells are transmitted via an ATM switch. For transmission of ATM cells related to Internet data packets from the ATM cell stream, the destination address information for the Internet data packets is transmitted to the ATM communications system from a connected ATM communications terminal with the aid of a special ATM cell. Routing information is derived from the destination address information in the ATM communications system. The derived routing information is then inserted into each ATM cell in an Internet data packet, for transmission via an ATM communications network.
The document IEE, 1996, Flow Labelled IP: A Connectionless Approach to ATM, Peter Newman et al. discloses an ATM communications network in which a local area network LAN is emulated for the connection of internet communications terminals. A xe2x80x9cConnectionless ATMxe2x80x9d is provided for the transmission of the Internet data packets. Within the ATM communications network, signalling in accordance with the ATM Adaption Layer (AAL-5) is provided in the ATM communications systems.
The object on which the invention is based is to improve the integration of Internet in ATM communications networks. The object is achieved by the features of claim 1.
The major aspect of the invention is that the ATM communications systems for transmitting data and data packets packed into ATM, cells are additionally provided, for transmitting Internet data packets, with means for selecting ATM cells related to Internet data packets from the ATM cell stream, means for finding Internet data packet headers from the selected ATM cells and means for extracting the destination address information contained in Internet data packet headers. Additional means are advantageously provided for sorting the transmitted ATM cells to form the respective Internet data packets and means for collecting the sorted ATM cells on the basis of specific Internet data packets and for passing on Internet data packet ways.
The complete integration of the Internet routing function in the ATM communications systems allows the ATM cell stream within the ATM communications network to be considerably reduced, since there is no need for the Internet data packets to be routed, possibly via a number of ATM communications systems, to the relevant Internet ATM routers. This means that it is possible to dispense entirely with the Internet ATM routers, and the integration of the Internet routing function in the ATM communications systems can be achieved with little additional circuitry and programming complexity. The already existing components of the ATM communications systems remain unchanged, that is to say they do not need to be modified.
The integration results in very short delays for the Internet data packets to be transmitted, since there is no routing to Internet ATM routers. A further advantage can be seen in integration, in particular retrospective integration, in that there is no effect on ATM traffic that is not related to Internet data packets. Furthermore, a universal ATM communications network can be provided for various types of traffic and service, which can be configured and matched to the respective requirements with very little effort, depending on user requirements, and the Internet routing function can be retrofitted or removed at any time.
For integration of the additional means for transmitting ATM cells related to Internet data packets, these are advantageously assigned to the individual system components as a function of the system architecture of the ATM communications systemxe2x80x94claim 3. In this case, both the concept of the ATM communications system with ATM multiplexers, line termination units, ATM switching networks and alternatively from ATM statistics multiplexers, and the fundamental ATM switching principle within the ATM communications system need to be taken into accountxe2x80x94for example the self-routing principle using communications-system internal headers and a connection identification. It is particularly advantageous for the additional means for transmitting ATM cells related to Internet data packets to be integrated between the communications connections and the ATM switching networkxe2x80x94claim 4xe2x80x94, since, in this case, the integration takes place directly in the data path, that is to say in the existing transmission path for ATM cells. Transmission of additional information for determining the routing information within the ATM communications system is largely avoided with such integration.
Five advantageous implementation versionsxe2x80x94claims 5 to 9xe2x80x94are possible for the integration of the additional means for transmitting ATM cells related to Internet data packets, which are based on an ATM communications system concept in which line units which provide ATM communications connections are connected to at least one ATM multiplexer for multiplexing ATM cells transmitted by the line units, and at least one ATM statistics multiplexer, which is connected on the input side to ATM multiplexers, is provided for buffer storage and for statistical distribution of the ATM cells, as well as an ATM switching network which is connected to the at least one ATM statistics multiplexer.
The most advantageous integration in an ATM communications system conceived in such a way is represented by the integration of the additional means for transmitting ATM cells related to Internet data packets in the stastistics multiplexerxe2x80x94claim 6. In this case, a single buffer store can advantageously be used for the buffer storage of ATM cell queues not only for ATM cells related to Internet data packets but also for ATM cells which are not related to Internet data packets, and the existing means for inserting ATM cells to be transmitted to the ATM switching network or to the ATM multiplexer are also used. Furthermore, [lacuna] are included by the integration of the additional means for transmitting ATM cells related to Internet data packets into the Traffic Management and Quality of Service Procedures, which have been standardized at the ATM forum and are implemented in the ATM statistics multiplexer. In this case, the Internet links can be included on the basis of their service class in the overall concept of the ATM communications system for handling ATM links in different classesxe2x80x94for example xe2x80x9creal timexe2x80x9d or xe2x80x9cnon-real timexe2x80x9d links with an UBR (unspecified bitrate), ABR (available bitrate) etc., as a result of which the integration complexity is considerably reduced.
One advantageous development of the communications system according to the invention can be seen in that, for transmitting ATM cells related to the Internet with predetermined, virtual path information and/or virtual channel information, means are provided for selecting ATM cells related to Internet data packets as a function of the predetermined virtual path information and/or virtual channel informationxe2x80x94claim 13. The assignment or specification of specific virtual paths for Internet data packets allows an advantageous implementation for the indentification of ATM cells related to Internet data packets. When transmitting using the self-routing principle and when transmitting ATM cells related to Internet data packets using predetermined routing information (which is derived from the virtual path information and/or virtual channel information and is internal to the communications system) and a connection identification, means are provided for selecting ATM cells related to Internet data packets as a function of the predetermined routing information (which is internal to the communications system), and a connection identificationxe2x80x94claim 14.
According to a further advantageous refinement of the ATM communications system according to the invention, the means for extracting the destination address information contained in Internet data packet headers comprise means for finding the destination address information inserted in the Internet data packet headers and means for passing on the destination address information to the means for deriving routing information from the destination address informationxe2x80x94claim 15. These means are normally implemented as programs in the ATM statistics multiplexer.
According to a development of the ATM communications system according to the invention in that the following items are provided for ATM cells related to Internet data packets with Internet multicast destination address information in the Internet data packet header: means for assigning further routing information to Internet multicast destination address information in the routing table, and means for copying the respective ATM cells and for introducing in each case one further routing information itemxe2x80x94claim 19. Storage of a number of communications network routing information items relating to Internet destination address information makes it possible to copy and transmit ATM cells related to Internet data packets to a number of ATM communications systems in the ATM communications network, in which case further xe2x80x9cmulticastxe2x80x9d routing information is determined and inserted in the ATM communications systems which have received these ATM cells, possibly after further assessment of the Internet destination address information.
Further advantageous refinements of the invention can be found in the further claims.